Modem - router problem

I have a LAN behind an ADSL Modem and a Router. Throught the modem alone
the internet works. With the modem AND the router it doesn't work. Does
someone know why?

Here are the details:

ADSL Modem
----------
Zyxel Prestige 623 ME
User Name <number>@adslplus.ch
Password *********
Lan Setup
DHCP
DHCP Server
Client IP Pool Starting Address 192.168.1.2
Size of Client IP Pool 4
Primary DNS Server 0.0.0.0
Secondary DNS Server 0.0.0.0
Remote DHCP Server N/A

TCP/IP
IP Address 192.168.1.1
IP Subnet Mask 255.255.255.248

Router
------
Zyxel Prestige 814 Plus
LAN Setup
DHCP Setup
DHCP Server (checked)
IP Pool Starting Address 192.168.1.33
Pool Size 32
Primary DNS Server 0.0.0.0
Secondary DNS Server 0.0.0.0
LAN TCP/IP
IP Address 192.168.1.2
IP Subnet Mask 255.255.255.0

WAN-Setup
ISP
Encapsulation PPPoE
Service Name <blank>
User Name <number>@adslplus.ch
Password *********
IP
WAN Adress IP Assignment: Get automatically from ISP (Default)
(checked)

Thanks in advance!

Roger